Generally, heat-resistant styrene-based copolymers, for example aromatic vinyl-unsaturated nitrile-based copolymers such as styrene-acrylonitrile copolymer aromatics, have been widely used in a variety of industrial fields including office automation equipment such as computers, printers, and copying machines, home appliances such as televisions and stereo equipment, electric and electronic parts, automobile parts, and other miscellaneous goods due to having excellent moldability, rigidity, and electrical characteristics. Particularly, aromatic vinyl-unsaturated nitrile-based copolymers which can withstand high outdoor temperatures due to high heat resistance are used in special applications such as housings for home appliances, automobile interior materials, etc.
Further, excellent surface properties such as transparency are necessary for resins used as exterior materials such as food containers, but aromatic vinyl-unsaturated nitrile-based copolymers prepared by conventional preparation methods contain a large amount of oligomers, generating fumes and gas are during the processing of the aromatic vinyl-unsaturated nitrile-based copolymer and resulting in low processability and a decrease in surface properties of the manufactured product, heat resistance, and weather resistance. Accordingly, studies are underway to develop an aromatic vinyl-unsaturated nitrile-based copolymer having a low oligomer content while maintaining the inherent properties of an aromatic vinyl-unsaturated nitrile-based copolymer.
However, although aromatic vinyl-unsaturated nitrile copolymers having excellent impact resistance or excellent impact resistance and heat resistance have been developed through many studies, there is a lack of development of an aromatic vinyl-unsaturated nitrile-based copolymer having excellent impact resistance and heat resistance as well as a low oligomer content and excellent surface properties.
Therefore, it is necessary to develop an aromatic vinyl-unsaturated nitrile-based copolymer having improved surface properties in order to further improve the utility of the aromatic vinyl-unsaturated nitrile-based copolymer.